Arado Ar 232 - Design

Design

The Ar 232 design resulted from a tender offered by the Reichsluftfahrtministerium (German Air Ministry, RLM) in late 1939 for a replacement for the Ju 52/3m transport. Both Arado and Henschel were asked for rear-loading designs powered by two 1,193 kW (1,600 hp) BMW 801A/B radial engines, which was just entering prototype production and not currently used on any front-line designs. The Arado design beat out Henschel's after an examination of the plans, and an order for three prototypes was placed in 1940.

Wilhelm van Nes led the design of the Ar 232. He began at the cargo area, with a bay directly behind the "stepless cockpit" that was 6.6 m (21 ft 7¾ in) long, 2.3 m (7 ft 6½ in) wide and 2.0 m (6 ft 6¾ in) high. Typical designs of the era would use a side-mounted door for access, but the Ar 232 used hydraulically powered clamshell-doors on the rear of the bay with a ramp to allow cargo to be rolled into the hold. The tail control surfaces were mounted on the end of a long boom to keep the area behind the doors clear so trucks could drive right up to the ramp. This allowed the Ar 232 to be loaded and unloaded faster than other designs.

For short-field performance, the Ar 232 incorporated Arado's own "travelling flap" design for the entire rear surface of the wing. Even loaded to 16,000 kg (35,270 lb), it could take-off in 200 m (656 ft). This distance could be further reduced by using rocket assist (RATO) for take-off, and either parachutes or reverse RATO for landing.

The most noticeable feature of the Ar 232 was the landing gear. Normal operations from prepared runways used a tricycle gear, but the struts could "break", or kneel, after landing to place the fuselage closer to the ground and thereby reduce the ramp angle. An additional set of ten smaller, non-retractable twinned wheels per side supported the aircraft once the primary gear was "broken", or could be used for additional support when landing on soft or rough airfields. The aircraft was intended to be capable of taxiing at low speeds on its small wheels, thus being able to negotiate small obstacles such as ditches up to 1.5 m (5 ft) in width. The appearance of the row of small wheels led to the nickname "millipede". In flight, the main legs fully retracted into the engine nacelles, while the fixed support wheels remained exposed and the nose wheel only semi-retracted.

Normally operated by a crew of four, the pilot was the only member without two roles. The navigator operated a 13 mm (.51 in) MG 131 machine gun in the nose, the radio operator a 20 mm MG 151 cannon in a rotating turret on the roof, and the loadmaster a 13 mm (.51 in) MG 131 machine gun firing rearward from the extreme rear of the cargo bay above the cargo doors.